python实现整数序列求和

n=input("请输入整数N：")
sum=0
for i in range(int(n)):
    sum+=i+1
print("1到N求和结果：",sum)

n = int(input('请输入想求和的数字：'))
print(sum(range(1,n+1)))

from functools import reduce
 n = int(input('请输入想求和的数字：'))
 print(reduce(lambda a,b:a+b,list(range(1,n+1))))

n = int(input('请输入想求和的数字：'))
sum = 0
for i in range(1,n+1):
    sum = sum + i
print(sum)

a = int(input('请输入想求和的数字：'))
 def fun(n):
     if n == 1:
         return n
     n = n + fun(n-1)
     return n
 print(fun(a))